A challenge for parasites is how to evade the
sophisticated detection and rejection abilities of potential
hosts. Many studies have shown how insect social parasites
overcome host recognition systems and successfully enter
host colonies. However, once a social parasite has successfully
usurped an alien nest, its brood still face the challenge of
avoiding host recognition. How immature stages of parasites
fool the hosts has been little studied in social insects, though
this has been deeply investigated in birds. We look at how
larvae of the paper wasp obligate social parasite Polistes
sulcifer fool their hosts. We focus on cuticular hydrocarbons
(CHCs), which are keys for adult recognition, and use
behavioral recognition assays. Parasite larvae might camouflage
themselves either by underproducing CHCs (odorless
hypothesis) or by acquiring a chemical profile that matches
that of their hosts. GC/MS analyses show that parasite larvae
do not have lower levels of CHCs and that their CHCs
profile is similar to the host larval profile but shows a
reduced colony specificity. Behavioral tests show that the
hosts discriminate against alien conspecific larvae from
different colonies but are more tolerant towards parasite
larvae. Our results demonstrate that parasite larvae have
evolved a host larval profile, which overcomes the host
colony recognition system probably because of the lower
proportion of branched compounds compared to host larvae.
In some ways, this is a similar hypothesis to the odorless
hypothesis, but it assumes that the parasite larvae are covered
by a chemical blend that is not meaningful to the host.

A challenge for parasites is how to evade the
sophisticated detection and rejection abilities of potential
hosts. Many studies have shown how insect social parasites
overcome host recognition systems and successfully enter
host colonies. However, once a social parasite has successfully
usurped an alien nest, its brood still face the challenge of
avoiding host recognition. How immature stages of parasites
fool the hosts has been little studied in social insects, though
this has been deeply investigated in birds. We look at how
larvae of the paper wasp obligate social parasite Polistes
sulcifer fool their hosts. We focus on cuticular hydrocarbons
(CHCs), which are keys for adult recognition, and use
behavioral recognition assays. Parasite larvae might camouflage
themselves either by underproducing CHCs (odorless
hypothesis) or by acquiring a chemical profile that matches
that of their hosts. GC/MS analyses show that parasite larvae
do not have lower levels of CHCs and that their CHCs
profile is similar to the host larval profile but shows a
reduced colony specificity. Behavioral tests show that the
hosts discriminate against alien conspecific larvae from
different colonies but are more tolerant towards parasite
larvae. Our results demonstrate that parasite larvae have
evolved a host larval profile, which overcomes the host
colony recognition system probably because of the lower
proportion of branched compounds compared to host larvae.
In some ways, this is a similar hypothesis to the odorless
hypothesis, but it assumes that the parasite larvae are covered
by a chemical blend that is not meaningful to the host.